UNIVERSITY OF SCIENCE TECHNOLOGY OF CHINA DOCTOR S DEGREE DISSERTATION TITLE AUTHOR SPECIALITY ADVISOR Studies on monolayer covalent modification of c

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1 UNIVERSITY OF SCIENCE AND TECHNOLOGY OF CHINA

2 UNIVERSITY OF SCIENCE TECHNOLOGY OF CHINA DOCTOR S DEGREE DISSERTATION TITLE AUTHOR SPECIALITY ADVISOR Studies on monolayer covalent modification of choline and choline derivatives on carbon electrodes for fabrication of electrochemical biosensors Guan-Ping Jin Analytical Chemistry Professor Xiang-Qin Lin

choline and choline derivatives on carbon electrodes for fabrication of

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----------------------------------------------------------1 1-2-1 ---------------------------------------------------------------------------------- -2 1-2-2

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5 (XPS) (UV-vis) (EIS) (Ch) (ACh) (PCh) (BuCh) (CCh) (-OH) (-O-) - (ACh/GCE) (DA) 5 (5-HT) AA CV DPV DA DA 5-HT AA GEC DPV I

6 DPV DA 5-HT AA (PCh/GCE) AA DPV 360 mv 47 mv (UA) 470 mv 293 mv UA AA DPV UA (BuCh/GCE) (Trp) (Tyr) BuCh/GCE Vamin (CCh/WGE) (SWV) mv γ (Ch-Glu/GCE) NO V 8 NO - 2 NO ~ mol/l mol/l(3 ) II

(CCh/WGE) (SWV) 50 100 mv 5 10 - -γ - - - (Ch-Glu/GCE) NO -

7 Abstract The detailed review for the covalently modified carbon electrode and the pharmacology effects of choline (Ch) and its derivers was carried out. Based on the studies of amino acid modified carbon electrodes in our lab, choline and its derivatives modified carbon electrodes were successively prepared for the first time, and a mixed modification of choline and amino acids at carbon electrodes were also investigated. Thus, a series of adulterate covalent monolayer or mixed covalent monolayer carbon electrodes were obtained by using a single compound or two different compounds. These electrodes were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and UV-visible spectroelectrochemical (UV-vis). In order to study the interaction among molecules, the electrochemical behaviors of the important biological substances including catechol, monoamine neurotransmitter, amino acid, estrogens etc. were investigated. Moreover, the various capabilities of the modified layers including restraint pollution, analysis in medicine, especially, analysis in biological samples were investigated. The dissertation is mainly focused on the following aspects: The choline (Ch), acetylcholine (ACh), propionylcholine (PCh), butyrylcholine (BuCh) and carbamylcholine (CCh) modified carbon electrodes were fabricated using the method of anodic oxidation. The reaction scheme was proposed based on the experimental results, which was the glassy carbon electrode (GCE) could be oxidized and cation radicals were formed on the surface. Then the surface cation radicals reacted with the hydroxyl group of choline through nucleophilic attack forming O ether bound linkages. Choline derivatives including ACh, PCh, BuCh and CCh could hydrolyze to Ch and carboxylic acid at the electrode surface firstly, then, the Ch was covalently bounded on the electrode surface during the anodic oxidation accompanying the carboxylic acid residue embedding and adsorbing by electrostatics in the Ch film, forming a novel choline/carboxylic acid alternation interring assembly, having adulterate covalent monolayer from the same ester molecules. III

modification of choline and amino acids at carbon electrodes were also investigated.

8 Due to Ch and its derivatives can produce various biology efficacies by affecting the synthesis, stockpile, release, metabolization of neurotransmitters. Therefore, the electrochemical behavior of a series selected bio-compounds including catechol, monoamine neurotransmitter, amino acid, estrogens etc. were investigated. The results validated that the redox of these substances probably occurred accompanying these biology efficacies. The preliminary application showed strong electrocatalytic function of acetylcholine modified GCE (ACh/GCE) to dopamine (DA), serotonin (5-HT) and ascorbic acid (AA), shifting their oxidation potentials negatively with greatly enhancing peak currents in either CV or DPV, and improving redox reversibility of DA. Thus, ACh/GCE can resolve the oxidation signals of DA, 5-HT and AA into three well-defined peaks in DPV. Under the optimal conditions, the proposed analytical method was applied to the simultaneous determination of DA, 5-HT and AA in mixture samples with satisfactory results. These modified electrodes have high stability, selectivity and reliability. Due to the strong electrocatalytic function of propionylcholine modified GCE (PCh/GCE) to UA and AA, shifting the oxidation potentials of UA and AA negatively by V and V to V and V vs SCE, respectively, and greatly enhancing the peak current of UA. PCh/GCE can separate the overlapping oxidation peaks of UA and AA into two distinct oxidation peaks in DPV. It can be used for the selective determination of UA in the presence of a higher concentration of AA (0.1 mmol/l). This method was successfully applied to the analysis of urine samples. The butyrylcholine modified GCE (BuCh/GCE) showed outstanding electrocatalytic function to tyrosine (Tyr) and tryptophan (Trp) in comparison with other choline derivatives modified electrodes. The BuCh/GCE can be successfully used to determine the total content of Tyr and Trp in Vaim, a mixed amino acids injection solution. The electrochemistry of estrogens including estradiol, estrone and estriol were respectively investigated at the carbamylcholine modified paraffin-impregnated graphite electrode (CCh/WGE). The CCh/WGE had excellent electrocatalytic IV

The results validated that the redox of these substances probably occurred accompanying these biology efficacies.

9 function to their oxidation, reducing their oxidation potentials by 0.05 V to 0.10 V vs SCE, and enhancing their oxidation peak currents of square wave voltammetry (SWV) about 5 to 10 times. Successful analyses of the total amounts of these estrogens in blood serums of pregnant women indicated that proposed analytical procedure was valuable in clinical analysis. Based on amino acid and choline (Ch) modification, a series of mixed covalent monolayer electrodes modified by choline and amino acid, including choline - glutamic acid (Glu-Ch/GCE), choline - glycine acid (Gly-Ch/GCE), choline - γ-minoburytic acid (Aba-Ch/GCE), were prepared. Among these, the Glu-Ch/GCE showed superior electrocatalytic function to DA, this improved the electrochemical behavior of DA, overcome adsorption of substance with charge, and restrain the pollution of DA redox products. Moreover, the Ch-Glu/GCE showed an excellent electrocatalytic function to NO - 2, shifting the oxidation potentials 0.32 V vs SCE negatively and increasing the peak current by eight times. The peak current was linearly related to the NO - 2 concentration over the range of to mol/l. The real detection limit was mol/l (3 ). These choline - amono acids modified electrodes have high stability, good ability of restraint pollution. V

Based on amino acid and choline (Ch) modification, a series of mixed covalent monolayer electrodes modified by choline and amino acid, including choline - glutamic acid (Glu-Ch/GCE), choline -

10 Barbier [1] Pinson [2] Ohmoir [3] Saveant [4] Nowall [5,6] 1-2 1

11 1-2-1 [1,7] C-N Barbier Pinson ( 1) e - GCE + R-NH 2 GCE + R-N + -H + H 2 GCE NH-R [7] Hoekstra 6- - [8] X (XPS), N(1s)/C(1s) 60% Porter (HOPG) XPS HOPG [7] XPS [1,7-9] [1,7,10] (EIS) [11] 2

12 30 min XPS N(1s) [1] (10-9 Torr) (110 C) XPS 0.1 mol/l HClO 4 0.2~0.8 V 100 XPS N(1s)/C(1s) 10% [7] [57] [1,10,11] Barbier Pinson[1] 4- XPS 25% 75% [10] (EIS) 9 µf/cm 2 4µF/cm 2 [11] XPS γ- [12-16] ACN/NBu 4 BF 4 ( ) C-N XPS XPS N(1s) ev C-N mol cm -2 3

13 1-1-1., 1,11,12 1, N N N- 7 N- 7 N γ

14 [21-23] Ohmoir Ohmori mol/l LiClO 4 3- (0~2.0 V vs. SCE) Fe(CN) 6 1- [3] 4- Ohmoir ( 1-1-2)[3,24-27] -0.5~1.5 V 0.1 mol/l NaCl GCE anodic oxidation -e GCE HOR GCE OR Ohmoir n-c n H 2n+1 OH(n=2,4,6,) HO(CH 2 ) n OH (n= 2~5) HO(CH 2 CH 2 O) 2 CH 2 CH 2 OR(R=H, Me) XPS [26] ( ) Fe(CN) 3-6 (64 ο ) 39 ο 5

1 mol/l NaCl 1-1-2 1-1-2 GCE anodic oxidation -e GCE.

15 ,27 3,25,26,27 1-3,27 1-3,26,27 1-3,27,29 1-3,26,27 1-3,27 1-3,26,27,30, ,27,30, ,26,29, ,26, , ,29 31,32 25, , [26,28] C m = ε ο k / d 1-1 ε ο F/cm k Fe(CN) 3-6 Fe(CN)

1-3,26,27,30,31 4-3 26,27,30,32 1 2-25,26,29,30 1 3-25,26,29 1

16 Fe(CN) 3-6 [26] Ohmoir 1.0 mol/l NaClO 4 [26] Pinson [2] ( 1-1-3) C-C R -NO 2 -COOH -Br -Cl [2,33-46] (ph>2) [47,48] [2,33-46] HOPG [2,37,39,42-44,47,51,52] [48] [49] [50] GCE + R N e - GCE + R -N 2 GCE R [39] XPS[2,33,39,40,41,43,47,49-50,52] (FTIR) [39] 7

UNIVERSITY OF SCIENCE & TECHNOLOGY OF CHINA MASTER S DEGREES DISSERTATION TITLE AUTHOR SPECIALITY ADVISOR Multichannel Electrogenerated Chemiluminesce

中国科学技术大学硕士学位论文论文题目 : 中性和碱性的鲁米诺体系在纳米银修饰电极上的多通道电致化学发光作者姓名 : 学科专业 : 王成名分析化学导师姓名 : 崔华教授完成时间 : 2006 年 5 月 UNIVERSITY OF SCIENCE & TECHNOLOGY